1. Field of the Invention
The present invention relates to a suspension seatpost, and more particularly to a suspension seatpost for the seat of a bicycle.
2. Description of the Related Art
A conventional suspension seatpost (1) in accordance with the prior art shown in FIG. 3 is used for a bicycle and comprises a fixed tube (11) secured in the seat tube (30) and containing a chamber (110) therein, an abutting block (112) secured in the chamber (110) of the fixed tube (11), a slide rod (12) slidably mounted in the fixed tube (11) and having its upper end secured to the seat (2) by means of a connector (14), and a spring (13) mounted between the abutting block (112) and the lower end of the slide rod (12).
When the bicycle is subjected to vibration such as on a rugged road, a force will be exerted on the frame (3) to move the frame (3) upward. The slide rod (12) is then moved downward in the chamber (110) relative to the frame (3) to compress the spring (13), thereby providing a shock absorbing function so as to prevent the shock from being directly transmitted to the seat (2).
However, the spring (13) has a great stiffness such that the spring (13) will produce a small amount of deformation during the compressing process thereof. Consequently, the spring (13) cannot completely absorb the most of energy from vibration, thereby decreasing the shock absorbing effect of the suspension seatpost (1). The present invention has arisen to mitigate and/or obviate the disadvantage of the conventional suspension seatpost.